Re: [PATCH 0/7] perf updates and fixes

[Frederic Weisbecker <fweisbec@gmail.com>]

On Fri, Mar 26, 2010 at 05:02:30PM +1100, Paul Mackerras wrote:
> On Fri, Mar 26, 2010 at 02:52:35AM +0100, Frederic Weisbecker wrote:
> 
> > The series is not yet mergeable because it would break PowerPc
> > (hot regs snapshot API has been changed, and I don't know how
> > to update PowerPc for that).
> > 
> > But if you're fine with the ideas, I can integrate the necessary
> > changes to fix this, and also separate fixes and updates.
> 
> The patch below adds the necessary stuff for powerpc.  You could fold
> it into your "perf: Move perf_arch_fetch_caller_regs into a macro"
> patch, or keep it as a separate patch in the series (though that would
> make preserving bisectability more difficult).
> 
> There is a little difficulty in that you first create a 3-argument
> form of perf_arch_fetch_caller_regs and then remove one argument in a
> later patch, whereas my patch below just creates the 2-argument form.
> I'm sure you can resolve that one way or another.
> 
> The patch to add the old-style perf_arch_fetch_caller_regs for powerpc
> is sitting in the tip/perf/urgent branch but hasn't gone anywhere.
> I suppose we need to get Ingo to pull that branch into tip/perf/core
> and then include a revert patch in the series that switches to the new
> interface.  Alternatively, if the urgent branch isn't append-only then
> we could disappear it (the urgent branch would need to be rewound by
> one commit).



Thanks a lot, that's axactly what I needed.
I'll sort it out to not break things in the middle :)



> 
> Paul.
> ----------
> [PATCH] perf/powerpc: Implement perf_arch_fetch_caller_regs for powerpc
> 
> This adds the ability to get a hot register snapshot for powerpc,
> enabling us to get meaningful call chains for tracepoints and context
> switch events.
> 
> Signed-off-by: Paul Mackerras <paulus@samba.org>
> ---
>  arch/powerpc/include/asm/perf_event.h |   12 ++++++++++++
>  1 file changed, 12 insertions(+)
> 
> diff --git a/arch/powerpc/include/asm/perf_event.h b/arch/powerpc/include/asm/perf_event.h
> index e6d4ce6..5c16b89 100644
> --- a/arch/powerpc/include/asm/perf_event.h
> +++ b/arch/powerpc/include/asm/perf_event.h
> @@ -21,3 +21,15 @@
>  #ifdef CONFIG_FSL_EMB_PERF_EVENT
>  #include <asm/perf_event_fsl_emb.h>
>  #endif
> +
> +#ifdef CONFIG_PERF_EVENTS
> +#include <asm/ptrace.h>
> +#include <asm/reg.h>
> +
> +#define perf_arch_fetch_caller_regs(regs, __ip)			\
> +	do {							\
> +		(regs)->nip = __ip;				\
> +		(regs)->gpr[1] = *(unsigned long *)__get_SP();	\
> +		asm volatile("mfmsr %0" : "=r" ((regs)->msr));	\
> +	} while (0)
> +#endif